The Dark Tower Series by Stephen King. This has been the answer to this for a long time, and while there are other series that I love, that take over my life when I read them, these books inhabit me unlike anything else.

I still find myself saying “thankee sai” to people who don’t know what the hell I’m talking about. I have a fixation for turtles and roses that gives them an importance that probably seems mentally unbalanced. I urge myself not to forget the face of my father. I urge others to have long days and pleasant nights. I kill with my heart, motherfucker.

When I get going on these books, I get so worked up that, before I even realize it, I’m gesturing wildly and my voice is overflowing with passion. I tear up. I freak out, to put it plainly. I fangirl very, very hard. Even when it’s been awhile since I visited Roland’s world, I still do that. So I think it has to be said, this is clearly my favorite.